MICHAEL VAUGHAN insists Australia will rightfully retain their world number one tag even if England dethrone them in the Ashes.

England captain Vaughan leads his side into the fifth Test at The Oval tomorrow needing to avoid defeat for a first series success in nine attempts over the old enemy.

Wins for Vaughan's men at Edgbaston and Trent Bridge, either side of the tense draw in Manchester, have led to Australia facing a series defeat for the first time since India came from behind four years ago.

But, even if England strengthen their hold on second place in the world standings, Vaughan has backed Australia's statistical superiority.

"Over periods of time the International Cricket Council rankings would suggest Australia would still be number one," said Vaughan.

"For us to be number one we have to do it over a more regular basis, as Australia have done over a five-year period."

For the first time in this campaign, England are faced with a selection issue put upon them by injury.

Until fast bowler Simon Jones was ruled out by an ankle injury, the hosts were on course to field the same XI for an entire series of five matches or more - an occurrence which last took place 120 years ago.

The logical replacement for Welshman Jones - whose 18 wickets cost just 21 apiece - would be Lancashire paceman James Anderson, although the inclusion of all-rounder Paul Collingwood is an option which Vaughan himself built a case for.

Handing Collingwood a third Test cap would lengthen the batting, theoretically making Australia's task of gaining 20 wickets more taxing, but would also leave the team with only four frontline bowlers.

"It is disappointing Simon has not come through but it gives one of those two players the chance to make a name for themselves in a huge game," Vaughan added..

"Our policy of playing five bowl-ers can be attacking but it can also be attacking playing an extra batsman and getting runs on the board.

"Considering there are seven weeks' rest afterwards, the actual workload for the bowlers is not a worry at this stage.

"Whichever way we go you can read it as being attacking or defensive. We will just try to make the right decision.

"It is a tough one but the result will not depend on which way we go. If we play a good, consistent game, the result will take care of itself. So we will just try to come up with the best formula to win at The Oval."

Both nations have been gripped by what has been billed as the best Test series England has ever hosted, such have been the thrilling finishes to the previous three matches.

"We are happy that the support is there for us," added Vaughan. We can try to perform to the level we have over the last three games and I am sure we can."